Preshaped Collagen membrane, Vertical ridge augmentation, Atrophic mandible, Guided bone Regeneration, titanium mesh.Aim: Evaluation of the efficacy of the pre-shaped resorbable membrane on increasing height of atrophic posterior alveolar ridge in mandible VS low profile titanium mesh by using CBCT scan.Patients and Methods: The study was conducted on 8 bilateral posterior mandibular sides of eight patients which were suffering from severe mandibular atrophy. Each patient was treated by vertical ridge augmentation by autogenous corticocancellous bone graft taken from anterior iliac crest of the same patient. In one mandibular side of each patient bone graft protected with titanium mesh (control group) and the other side in the same patient protected with pre-curved membrane (study group).The patients were followed up for six months postoperatively clinically and by conebeam computed tomograms immediately postoperative, which represented the base line radiographs and after six months, bone height was measured to compare amount of bone resorption of both groups.Results: All statistical tests were two sided and performed at a significance level of ^5; =.05 and by using Student’s T-test (Student’s t-test: t = 2.414, p < .05). The results showed a statistically significant difference between the resorption rate RR of the vertically augmented alveolar ridge under the membrane in the study group (n=8) and RR in the control group (n=8). The results showed increase in resorption rate in the study group more than the control group.Conclusion: The resorption rate in augmented bone is higher in sides where the membrane was used than the sides in which the Ti- mesh was used because the membrane loses its form and its rigidity by humidity before consolidation of the augmented bone.